1. Field of the Invention
The present invention relates to a process for the manufacture of hexamethylene diamine, and in particular, to a process for the manufacture of hexamethylene diamine from 2-cyanocyclopentanone, especially 2-cyanocyclopentanone mixed with adiponitrile.
2. Description of the Prior Art
Adiponitrile can be obtained by reacting adipic acid with ammonia in the presence of a dehydrating catalyst, for example, by the techniques disclosed in U.S. Pat. No. 2,200,734 to Arnold and Lazier issued on May 14, 1940 and in U.S. Pat. No. 2,273,633 to M. L. A. Fluchaire, issued on Feb. 17, 1942. The catalytic hydrogenation of dicyanobutene to adiponitrile is described in U.S. Pat. No. 2,532,311 to B. W. Howk and M. W. Farlow, issued on Dec. 5, 1950. Adiponitrile produced by these processes contains impurities, some of which boil at temperatures close to the boiling point of adiponitrile, e.g. 2-cyanocyclopentylideneimine. Impurities in the adiponitrile may lead to impurities in subsequent derivatives, in particular in hexamethylene diamine, that are difficult to remove. Failure to remove these latter impurities may result in inferior and variable properties, especially in polymers manufactured using such impure hexamethylene diamine.
Adiponitrile can be purified by the process disclosed in U.S. Pat. No. 3,879,436, issued on Apr. 22, 1975 to B. J. Kershaw and M. G. Pounder. 2-Cyanocyclopentylideneimine in adiponitrile, may also be hydrolyzed to 2-cyanocyclopentanone using a solid acidic catalyst in the presence of water and at a temperature of at least 140.degree. C. The solid acidic catalysts may be silica-alumina catalysts, crystalline aluminosilicates, boron phosphate of titania-alumina as disclosed in U.S. Pat. No. 3,775,258 issued on Nov. 27, 1973 to B. J. Kershaw. The 2-cyanocyclopentanone is more easily separated from adiponitrile by techniques known in the art.